I've done quite a bot of research trying to decide on my first mechanical keyboard, but my needs are fairly specific, and there a few things I haven't been able to find answers for.

I'm using a raspberry pi 3 connected to a monitor as a dedicated word processing work station. I do a lot of text editing with no internet distraction this way, and it's also allowing me to learn to use linux, as well as vim and python. Since I spend so much time typing, I'd like to upgrade to a mechanical keyboard. Here's what I need:

1. Will work with the raspberry pi 3
2. Comfort for long typing sessions. (I'm mostly used to macbook type chicklet keyboards)
3. Reliability and longevity (I won't be able to buy multiple keyboards, so I want one good one)
3. TKL, or ~60% (I have very limited desk space, plus I am drawn to the minimalist aesthetic)

So far this is what appeals to me:

1. HHKB Pro2 (I'm not sure how I will adjust to the lack of dedicated arrow keys, but I love everything else I've read)
2. Leopold FC660C
3. Leopold FC660M (Much cheaper, but not sure which switches would be best. I'd like some tactile feel. Can't be too noisy. And needs to be comfortable for hours of typing at a stretch)
4. If I could manage without the arrow keys, there look to be a lot of other options that are cheaper than the topre keyboards in the 60% or under category. There seems to be high regard for the comfort of the topre boards, so I'm leaning in that direction, but I'm open to other suggestions. I'm not eager to spend that kind of cash, but I'm willing if it's the right choice.

Again, first and foremost, I'm hoping someone can confirm functionality with the raspberry pi 3 for any of these models, or others. Then I can narrow down from there. Thanks.

Mac is the only one with keyboard compatibility issues, Drevo and Noppoo due to their implementation of n-key rollover.

Everything you picked should work just fine.

Thank you! I'd been under that impression, too, based on some searches I've done. But there was one post elsewhere (admittedly, from a few years ago) that mentioned a problem with the HHKB and the raspberry pi, and there was speculation that it might be due to a low power issue. Unfortunately, the thread was left unresolved, and I've not found any direct confirmation of anyone using this exact combination successfully. I'm a pretty new linux user, so I don't have much insight of my own. I'm really hoping someone here can report that they've tried it, and found it to work the way it should. Would make me feel much less anxious about a purchase.

Definitely go with the powered hub.  We did some experimentation here at work with using Raspberry Pi's as thin clients and consistently had issues with keyboards and mice if they were plugged directly in (usually you could power one or the other but rarely both).  A powered hub takes care of that.

Other than that though keyboard compatibility itself is pretty good on a R Pi.  As long as it's on a powered hub I've never found anything to not work.  Since I use them as media players at home I use a lot of "keyboard emulating" remote controls with them and they even work with those quite well.

No, I've never had any trouble with any powered hub backfeeding any power.  The only one I have on hand that I know works though I don't see any model information on.  It's just a small hub that says "Ultra" on the top. 

This looks exactly the same but without a model number on the bottom of the other one I can't verify that they're the exact same part no.

http://www.tigerdirect.com/applications/SearchTools/item-details.asp?EdpNo=4475078